Landing gear warning switch cutout



June 30, 1942. A. l. OSTLUND ET AL LANDING GEAR WARNING SWITCH CUT-OUT Filed Nov. 29, 1941 Mn I Patented June 30, 1942 UMTED. S'iATES- PATENT @FllQE amazes LANDING eerie, WARNING swrrcn oU'roU'r Albion r. osiime and mine. Minshull/Seattlc, Wash, assignors to Boeing Air-omit Company, Seattle, Wash, a corporation oi washington Application November 29, 1941, Serial No..420,996 4 e a (or. 127-311;

It is customary practice, in airplanes which have retractable landing gears, to provide a sig= nal, usually a horn located closely adjacent the pilots ear, in a circuit which includes switch always at will deenerglze the signal, after it commences to sound, yet is assured that the signal will always be ready to sound again whenever it is proper that it should. I

Again, a further object is to provide such a warning signal out out, which is of simple construction, and sin pie to install, and which is located conveniently to the pilot as he operates the throttle lever that is closed when the landing gear is retracted, 5 With these .and other objects in mind, as will and to arrange to energize that signal by a appear hereafter, our invention comprises the normally open push button in the signal circuit, novel arrangement, and the novel parts thereof, located in the path of the throttle lever, such as shown in the accompanying drawing in a manner that as the throttle lever approaches or preferred form, and as will be hereinaiter more nearly reaches closed. position the horn is n fully explained anddefinedby the claims which sounded. Since the closing of the throttle is close this specification.

normal in gliding to a landing, the arrangement in the accompanying drawing the invention described serves to warn the pilot, should he has been shown diagrammatically and also in prepare to land while his landing gear is still a form which is at present preferred by us. retracted. Figure l is a side elevation of the throttle While such a warning signal has proven its lever, and of the associated cut-out. valuein numerous instances, there are other co Figure 2 is an enlarged view of the same, casions when. the pilot, in flight, may wish to taken at right angles to Figure 1. close his throttle and glide or dive, while his Figure 3 is a detail, partly in section and landinggear is still retracted. Such maneuvers g partly in elevation, illustrating the cut out and are particularly appropriate to fighter airplanes its relation to the throttle lever. engaged in individual combat, and it is distract- Figure 4 is a diagrammatic illustration of the ing to have a signal horn sounding at such principles of the invention. times. However, while it is a simple matter to Referring first to Figure 4, the throttle lever i provide a cut-out switch in the signal circuit, ii is rotatably mounted to move about the axis Ml, there is such a switch it may happen that the and the landing gear, generally indicated by pilot willturn oil the signal and forget to close the numeral 4, is mounted for retraction to the switch again, and then he may attempt to swing about the axis 40. The warning signal 3 land with his landing gear up, and will-receive may be considered as an electric diaphragm no warning signal as he starts his glide. It fol- '11" horn, and in its circuit is included an energy lows that it isdangerous to provide such a cutsource 30, a self-closing switch 34, which is out switch, or a similar cut-out arrangement, opened only as the landing gear reaches its proand so heretofore the pilot has been faced with jected or landing position, and a normally open the dilemma of enduring the horn whenever in switch 3|, the movable push button 33 of which flight he closes his throttle, or of risking the 35 is disposed in the path of the throttle lever or of possibility of a landing with his landing gear some member which moves with the latter. The up, or it has been necessary to provide a signal circuit may also include a switch 32, mechanically and electrically complicated shutwhich is normally closed but which can be used of! system, with the always-present possibility to deenergize the entire circuit at will. This of failure, and'of consequent disaster. 4D switch preferably is located in a relatively in-v Itisthe object of thepresent invention to proaccessible spot, where it is not likely to be vide a device for incorporation in and in conopened by the pilot while in flight, except in nection with such a warning signal system, case of emergency.

' whereby the pilot at will can deenergize the The movement of thethrottle lever! between warning signal, but which will automaticallyopopen and closed positions is under the control erate by advance of the throttle toward open of the pilot, and the limits of its movement are position to place the signal in condition for determined by suitable stops, not shown. It is operation againjwhenever the throttle is next so arranged with relation to the 'movable memmoved toward or substantially to closed posi-- ber 33 of the actuating switch 3| that the buttion. By such sin-arrangement the pilot can ton 33 is not depressed by the throttle lever,

even when the latter reaches its full closed position, which full, closed position is represented -at C in Figure 1. However, a spacer member 2 switch 3|.

ried upon the throttle lever and thebutton' 33. This spacer member is of such size that it is contacted by the spur II when the throttle lever reaches the point B, just prior to its reaching I its closed position C. When the spacer member 2 is thus contacted and moved by the throttle lever it transmits this movement to the button 33, and thereby the signal 3 is energized if the landing gear 4 is still retracted. To permit such movement of the spacer member 2 it may conveniently be formed as an arm or finger pivotally mounted upon a pivot post 20, supported in a fixed bracket 2| which also supports the Whether it is mounted upon the bracket or upon the throttle arm is largely immaterial.

In order to enable the spacer member 2 to be held normally in its operative position, interfrom between the throttle-lever and the actuator, to deenergize the signal at will, and means active upon reverse movement of the throttle lever'to can not be moved for signal energization, a

posed between the throttle lever and the switch,

yet to 'be moved at will from such operative position, it is movable bodily axially along the post by pressing upon the handle 22, in opposition to the spring 23.

As will now be evident, the spacer member 2 is held by the spring 23, normally in interposed position, where it will transmit movement of the throttle lever, as the latter nears closed position, to the switch to energize the signal. However, if the pilot wishes to deenergize the signal he has only to press upon the handle 22, and thereby the spacer member 2, even though swung aside as shown in dot-dash lines in Figure 2, may be depressed below the spur ll. When so depressed it may not move back into interposed position, being held by the spur, but immediately the throttle lever and its spur l l are moved towards open position the spring 23 moves the spacer member 2 back into its normal interposed position. The end of the button 33 is shaped to position.

guide the deflected finger 2 backto its normal Now, if the throttle lever is again moved toward closed position, automatically, and without thought on the part of the pilot, the signal is again energized. If the pilot desires to deenergize it, this must be done positively, and

position. Always after movement of the throttle away from closed position the signal circuit is again placed in condition for energization, without any thought or conscious action on the part of the pilot.

The entire device is simple, light, and requires spacer member fixedly positioned relative to the actuator, of a size and so disposed as to transmit final closing movement of the throttle lever to the actuators movable element, for signal energization, a support for the spacer member arranged to afford such movement of the spacer after each return of the throttle toward closed member with thethrottle lever and actuator, and to afford also manual movement of the spacer member relative to the actuator and from its interposed position, thereby to deenergize the signal at will, means to interdict return of the spacer member to its interposed position following its signal energizing movement and prior to reverse movement of the throttle lever, and resilient means active upon the spacer member to return it to its interposed position immediatelyfollowing movement of the throttle lever towards open position.

3. In combination with the throttle lever of an airplane, movable in a fixed path between open and closed positions, and with the retractable landing gear, a signal, means to energize said signalif the throttle lever is moved substantially to closed position while the landing gear is retracted, said signal-energizing means including a spur projecting from the throttle lever in the plane of its movement, a fixedly positioned actuator having a moyable element disposed in the path of the spur, but spaced sufllciently therefrom, in closed position, that the spur can not move such element for energization of the signal, a spacer member normally interposed between the spur andthe movable element of the actuator, of a size to transmit movement I of the throttle lever to the movable actuator no wiring connections. It is always in position for use, conveniently to the-pilot as he operates the throttle lever, and it is always ready for operation. 1

What we claim as our invention is:

' 1. In combination with the throttle lever of anairplane, movable in a fixed path between open and closed positions, and with the retractable landing gear, a signal, means to energize said signal if the throttle lever is moved subgear is retracted, said means including an actuator disposed in the path of the throttle lever, but spaced sufiiciently from the latter, in its closed position, that the actuator can not be operatively engaged for energization of the sigstantially to closed position while thelanding nal. a spacer member normally interposed between the actuator and the throttle lever, of a size to span the gap therebetween, for energiza- 'tion of the signal as the throttle lever substantially reaches closed position, a support for said spacer member permitting its movement at will element, for energization of the signal as the throttle lever approaches closed position, a support for the spacer member arranged to afford movement of the spacer by and with the spur,

and also manually transversely of the spur into inoperative position wherein it is held by the spur, and spring means active upon withdrawal of the spur and throttle lever towards open position, .to restore the spacer member immediately to its normal interposed position.

4. The combination of claim 2, wherein the spacer member comprises a finger and a pivot support therefor the axis whereof is generally parallel to but offset from the throttle levers path, said spacer member being mounted upon said pivot support for swinging movement upon engagement of its outer end by the throttle lever, and for'bodily axial movement "into and from its inoperative position.

ALBION I. OSTLU'N'D. JOHN A. MINSHULL'. 

